Soil Erosion and Sediment Production on Watershed Landscapes: Processes and Control Authors: International Hydrological Programme for Latin America and the Caribbean Peter F. Ffolliott Kenneth N. Brooks Daniel G. Neary Roberto Pizarro Tapia PHI-VII / Documento Técnico N° 32 Pablo García Chevesich Soil Erosion and Sediment Production on Watershed Landscapes: Processes, Prevention, and Control Authors Peter F. Ffolliott, Professor Emeritus School of Natural Resources and the Environment University of Arizona, Tucson, Arizona Kenneth N. Brooks, Professor Emeritus Department of Forest Resources University of Minnesota, St. Paul, Minnesota Daniel G. Neary, Soil Scientist Rocky Mountain Research Station, U.S. Forest Service, Flagstaff, Arizona Roberto Pizarro Tapia, Director Centro Tecnológico de Hidrología Ambiental Universidad de Talca, Talca, Chile Pablo Garcia-Chevesich, Researcher Environment, Environmental Service, and Water Government of Chile Published in 2013 by the International Hydrological Programme (IHP) of the Regional Office for Science for Latin America and the Caribbean of the United Nations Educational, Scientific and Cultural Organizations (UNESCO). ISBN 978-92-9089-190-1- Soil Erosion and Sediment Production on Watershed Landscapes: Processes and Control Documento Técnico del PHI-LAC, Nº 32 © UNESCO 2013 The designations employed and the presentation of material throughout the publications do not imply the expression of any opinion whatsoever on the part of UNESCO concerning the legal status of any country, territory, city or of its authorities, or concerning the delimitation of its frontiers or boundaries. The authors are responsible for the choice and the presentation of the facts contained in this book and for the opinions expressed therein, which are not necessarily those of UNESCO and do not commit the Organization. This publication may be reproduced in whole or in part form for education or nonprofit use, without special permission from the copyright holder, provided acknowledgement of the source is made. As a courtesy the authors should be informed of any use made of their work. This publication should be cited as: UNESCO, 2013. Soil Erosion and Sediment Production on Watershed Landscapes: Processes and Control. Peter F. Ffolliott, Daniel G. Neary, Kenneth N. Brooks, Roberto Pizarro Tapia, Pablo García Chevesich, Documentos Técnicos del PHI-LAC, N° 32 Free copies of this publication should be requested to: Programa Hidrológico Internacional para Facultad de Ciencias Forestales América Latina y el Caribe (PHI-LAC) Universidad de Talca Oficina Regional de Ciencia para Avenida Lircay S/N América Latina y el Caribe Talca, Chile UNESCO Tel.: 56 71 200 442 / 200 440 Dr. Luis P. Piera 1992, 2º piso Fax: 56 71 200 455 / 428 11200 Montevideo, Uruguay http://www.cienciasforestales.cl Tel.: 598 2413 2075 Fax: 598 2413 2094 E-mail: [email protected] http://www.unesco.org.uy/phi CONTENTS Chapter One - INTRODUCTION 1. Losses of Soil Resources ....................................................................................................................................... 7 2. The Purpose of This Publication ........................................................................................................................... 7 3. Organization of the Publication ............................................................................................................................. 8 4. References ............................................................................................................................................................. 8 Part I SOIL EROSION PROCESSES, PREVENTION, CONTROL Chapter Two - SURFACE EROSION 1. Introduction ........................................................................................................................................................... 9 2. Processes ............................................................................................................................................................. 9 3. Measurement of Surface Erosion .......................................................................................................................... 10 3.1. Erosion Plots .................................................................................................................................................. 10 3.2. Erosion Pins or Stakes .................................................................................................................................. 11 3.3. Natural Landscape Features.......................................................................................................................... 11 4. Prediction of Soil Loss .......................................................................................................................................... 11 4.1. Universal Soil Loss Equation........................................................................................................................ 11 4.1.1. Rainfall Erosivity Factor..................................................................................................................... 12 4.1.2. Soil Erodibility Factor ........................................................................................................................ 13 4.1.3. Slope Length and Slope Gradient Factors .......................................................................................... 14 4.1.4. Cropping Management Factor ............................................................................................................ 14 4.1.5. Erosion Control Practice Factor ......................................................................................................... 15 4.2. Modification of the Universal Soil Loss Equation ....................................................................................... 15 4.3. Soil Loss and Conservation Planning ........................................................................................................... 16 4.4. Revised Universal Soil Loss Equation.......................................................................................................... 16 4.5. Water Erosion Prediction Project Model ..................................................................................................... 17 5. Prevention of Surface Erosion ............................................................................................................................... 17 6. Control of Surface Erosion .................................................................................................................................... 18 6.1. Vegetative Measures .................................................................................................................................... 18 6.2. Mechanical Methods .................................................................................................................................... 18 6.3. Minimizing Impacts of Roads ..................................................................................................................... 19 7. Cumulative Effects on Surface Erosion ................................................................................................................ 19 8. Summary ............................................................................................................................................................. 20 9. References ............................................................................................................................................................. 20 Chapter Three GULLY EROSION 1. Introduction ........................................................................................................................................................... 23 2. Processes ............................................................................................................................................................. 23 3. Prevention of Gully Erosion .................................................................................................................................. 24 3 Soil Erosion and Sediment Production on Watershed Landscapes: Processes and Control 4. Control of Gully Erosion ....................................................................................................................................... 24 4.1. Establishment of Vegetation ........................................................................................................................ 24 4.2. Mechanical Methods .................................................................................................................................... 25 4.2.1. Check Dams ....................................................................................................................................... 25 4.2.2. Headcut Control ................................................................................................................................. 26 4.2.3. Vegetation-Lined Waterways ............................................................................................................. 27 5. Cumulative Effects on Gully Erosion ................................................................................................................... 27 6. Summary ............................................................................................................................................................. 28 7. References